This invention relates generally to valve seats and, more particularly, to a valve seat with an inlay and grooves for use in a machine, such as a turbine.
In variety of different applications, such as in a steam turbine, it is important to be able to control the flow of a motive fluid, such as steam, through the machine. To achieve this control, these applications typically employ the use of a valve assembly. Each of the valve assemblies is located in a passage in the machine and includes a stopper which can be moved between an open position exposing an opening to the passage and a closed position sealing the opening to the passage. To help form a seal between the passage and the stopper, the valve assemblies sometimes include a valve seat which is located in the passage and has a narrower passage.
Although the valve seat is helpful in forming a seal with the valve stopper, there are some problems with existing valve seats. For example, one problem with these valve seats is that over time the valve seats begin to corrode and/or erode away, particularly near the portion of the valve seat which engages with the valve stopper due to high velocities. As a result, the seal formed between the valve stopper and the valve seat often begins to deteriorate permitting motive fluid to leak through the fluid passage when the valve stopper is in a closed position.
Another problem with these existing valve seats is that the valve seats are not designed to control the flow of motive fluid in a laminar flow through the fluid passage.
Yet another problem with these and existing valve seats is that they can not handle higher velocity flow, e.g. flow at rates above 600 feet/second when the valve stopper is operating close to the valve seat.
A valve seat in accordance with one embodiment of the present invention includes a seat body with a channel and an inlay. The seat body has a passage which extends from a first opening to a second opening in the seat body. The channel is located in the seat body adjacent the first opening and extends around at least a portion of the passage. The inlay is located in at least a portion of the channel.
A valve seat in accordance with another embodiment of the present invention includes a seat body with at least one groove. The seat body has a passage which extends from a first opening to a second opening in the seat body. The groove extends along at least a portion of an inner surface of the passage from the first opening towards the second opening.
A machine in accordance with another embodiment of the present invention includes a housing with a fluid passage, a seat body with a channel and an inlay, and a valve stopper. The seat body is seated in the fluid passage in the housing and has its own fluid passage which extends from a first opening to a second opening in the seat body. The channel is located in the seat body adjacent the first opening and extends around at least a portion of the fluid passage in the seat body. The inlay is located in at least a portion of the channel. The valve stopper is moveable between a first position sealing against the first opening and at least a portion of the inlay of the seat body and a second position exposing the first opening.
A machine in accordance with another embodiment of the present invention includes a housing with a fluid passage, a seat body with at least one groove, and a valve stopper. The seat body is seated in the fluid passage in the housing and has its own fluid passage which extends from a first opening to a second opening in the seat body, the seat body. The groove extends along at least a portion of an inner surface of the passage from the first opening towards the second opening. The valve stopper is moveable between a first position sealing against the first opening of the seat body and a second position exposing the first opening.
With present invention the inlay in the channel or groove adjacent the first opening to the valve seat reduces the effects of corrosion and/or erosion to the valve seat. As a result, when the valve stopper is pressed against the valve seat to seal the first opening, the inlay helps to maintain the integrity of the portion of the valve seat near the first opening which seals against the valve stopper and thus permitting a seal to be achieved and maintained.
Additionally, with the present invention the corners or sharp edges of the grooves which extend along the fluid passage in the valve seat from the first opening towards the second opening in the valve seat redirect the flow pattern to cause laminarization of the motive fluid. More specifically, the grooves reduce the velocity of the motive fluid passing through the valve seat. The geometry of the grooves reduces the cyclonic effect inherent to fluids passing through an orifice or passage. The additional area provided by the grooves also allows for volumetric expansion of the motive fluid into this area which reduces the effects of the minor venturi caused from the geometry when the valve stopper is in close proximity to the first opening to the valve seat.
Further, by tapering the interior seat wall or surface of the passage from the first opening to the second opening in the valve seat and including the grooves along the inner surface of the fluid passage, a venturi effect is created which decreases the losses due to friction of the motive fluid passing through the valve seat because the grooves reduce the turbulence.